/*
 * Copyright (c) 2009-2016 Petri Lehtinen <petri@digip.org>
 *
 * Jansson is free software; you can redistribute it and/or modify
 * it under the terms of the MIT license. See MIT for details.
 */

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif

#include "jansson_private.h"

#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include "jansson.h"
#include "strbuffer.h"
#include "utf.h"

#define STREAM_STATE_OK        0
#define STREAM_STATE_EOF      -1
#define STREAM_STATE_ERROR    -2

#define TOKEN_INVALID         -1
#define TOKEN_EOF              0
#define TOKEN_STRING         256
#define TOKEN_INTEGER        257
#define TOKEN_REAL           258
#define TOKEN_TRUE           259
#define TOKEN_FALSE          260
#define TOKEN_NULL           261

 /* Locale independent versions of isxxx() functions */
#define l_isupper(c)  ('A' <= (c) && (c) <= 'Z')
#define l_islower(c)  ('a' <= (c) && (c) <= 'z')
#define l_isalpha(c)  (l_isupper(c) || l_islower(c))
#define l_isdigit(c)  ('0' <= (c) && (c) <= '9')
#define l_isxdigit(c) \
    (l_isdigit(c) || ('A' <= (c) && (c) <= 'F') || ('a' <= (c) && (c) <= 'f'))

/* Read one byte from stream, convert to unsigned char, then int, and
   return. return EOF on end of file. This corresponds to the
   behaviour of fgetc(). */
typedef int(*get_func)(void *data);

typedef struct {
	get_func get;
	void *data;
	char buffer[5];
	size_t buffer_pos;
	int state;
	int line;
	int column, last_column;
	size_t position;
} stream_t;

typedef struct {
	stream_t stream;
	strbuffer_t saved_text;
	size_t flags;
	size_t depth;
	int token;
	union {
		struct {
			char *val;
			size_t len;
		} string;
		json_int_t integer;
		double real;
	} value;
} lex_t;

#define stream_to_lex(stream) container_of(stream, lex_t, stream)


/*** error reporting ***/

static void error_set(json_error_t *error, const lex_t *lex,
	const char *msg, ...)
{
	va_list ap;
	char msg_text[JSON_ERROR_TEXT_LENGTH];
	char msg_with_context[JSON_ERROR_TEXT_LENGTH];

	int line = -1, col = -1;
	size_t pos = 0;
	const char *result = msg_text;

	if (!error)
		return;

	va_start(ap, msg);
	vsnprintf(msg_text, JSON_ERROR_TEXT_LENGTH, msg, ap);
	msg_text[JSON_ERROR_TEXT_LENGTH - 1] = '\0';
	va_end(ap);

	if (lex)
	{
		const char *saved_text = strbuffer_value(&lex->saved_text);

		line = lex->stream.line;
		col = lex->stream.column;
		pos = lex->stream.position;

		if (saved_text && saved_text[0])
		{
			if (lex->saved_text.length <= 20) {
				snprintf(msg_with_context, JSON_ERROR_TEXT_LENGTH,
					"%s near '%s'", msg_text, saved_text);
				msg_with_context[JSON_ERROR_TEXT_LENGTH - 1] = '\0';
				result = msg_with_context;
			}
		}
		else
		{
			if (lex->stream.state == STREAM_STATE_ERROR) {
				/* No context for UTF-8 decoding errors */
				result = msg_text;
			}
			else {
				snprintf(msg_with_context, JSON_ERROR_TEXT_LENGTH,
					"%s near end of file", msg_text);
				msg_with_context[JSON_ERROR_TEXT_LENGTH - 1] = '\0';
				result = msg_with_context;
			}
		}
	}

	jsonp_error_set(error, line, col, pos, "%s", result);
}


/*** lexical analyzer ***/

static void
stream_init(stream_t *stream, get_func get, void *data)
{
	stream->get = get;
	stream->data = data;
	stream->buffer[0] = '\0';
	stream->buffer_pos = 0;

	stream->state = STREAM_STATE_OK;
	stream->line = 1;
	stream->column = 0;
	stream->position = 0;
}

static int stream_get(stream_t *stream, json_error_t *error)
{
	int c;

	if (stream->state != STREAM_STATE_OK)
		return stream->state;

	if (!stream->buffer[stream->buffer_pos])
	{
		c = stream->get(stream->data);
		if (c == EOF) {
			stream->state = STREAM_STATE_EOF;
			return STREAM_STATE_EOF;
		}

		stream->buffer[0] = c;
		stream->buffer_pos = 0;

		if (0x80 <= c && c <= 0xFF)
		{
			/* multi-byte UTF-8 sequence */
			size_t i, count;

			count = utf8_check_first(c);
			if (!count)
				goto out;

			assert(count >= 2);

			for (i = 1; i < count; i++)
				stream->buffer[i] = stream->get(stream->data);

			if (!utf8_check_full(stream->buffer, count, NULL))
				goto out;

			stream->buffer[count] = '\0';
		}
		else
			stream->buffer[1] = '\0';
	}

	c = stream->buffer[stream->buffer_pos++];

	stream->position++;
	if (c == '\n') {
		stream->line++;
		stream->last_column = stream->column;
		stream->column = 0;
	}
	else if (utf8_check_first(c)) {
		/* track the Unicode character column, so increment only if
		   this is the first character of a UTF-8 sequence */
		stream->column++;
	}

	return c;

out:
	stream->state = STREAM_STATE_ERROR;
	error_set(error, stream_to_lex(stream), "unable to decode byte 0x%x", c);
	return STREAM_STATE_ERROR;
}

static void stream_unget(stream_t *stream, int c)
{
	if (c == STREAM_STATE_EOF || c == STREAM_STATE_ERROR)
		return;

	stream->position--;
	if (c == '\n') {
		stream->line--;
		stream->column = stream->last_column;
	}
	else if (utf8_check_first(c))
		stream->column--;

	assert(stream->buffer_pos > 0);
	stream->buffer_pos--;
	assert(stream->buffer[stream->buffer_pos] == c);
}


static int lex_get(lex_t *lex, json_error_t *error)
{
	return stream_get(&lex->stream, error);
}

static void lex_save(lex_t *lex, int c)
{
	strbuffer_append_byte(&lex->saved_text, c);
}

static int lex_get_save(lex_t *lex, json_error_t *error)
{
	int c = stream_get(&lex->stream, error);
	if (c != STREAM_STATE_EOF && c != STREAM_STATE_ERROR)
		lex_save(lex, c);
	return c;
}

static void lex_unget(lex_t *lex, int c)
{
	stream_unget(&lex->stream, c);
}

static void lex_unget_unsave(lex_t *lex, int c)
{
	if (c != STREAM_STATE_EOF && c != STREAM_STATE_ERROR) {
		/* Since we treat warnings as errors, when assertions are turned
		 * off the "d" variable would be set but never used. Which is
		 * treated as an error by GCC.
		 */
#ifndef NDEBUG
		char d;
#endif
		stream_unget(&lex->stream, c);
#ifndef NDEBUG
		d =
#endif
			strbuffer_pop(&lex->saved_text);
		assert(c == d);
	}
}

static void lex_save_cached(lex_t *lex)
{
	while (lex->stream.buffer[lex->stream.buffer_pos] != '\0')
	{
		lex_save(lex, lex->stream.buffer[lex->stream.buffer_pos]);
		lex->stream.buffer_pos++;
		lex->stream.position++;
	}
}

static void lex_free_string(lex_t *lex)
{
	jsonp_free(lex->value.string.val);
	lex->value.string.val = NULL;
	lex->value.string.len = 0;
}

/* assumes that str points to 'u' plus at least 4 valid hex digits */
static int32_t decode_unicode_escape(const char *str)
{
	int i;
	int32_t value = 0;

	assert(str[0] == 'u');

	for (i = 1; i <= 4; i++) {
		char c = str[i];
		value <<= 4;
		if (l_isdigit(c))
			value += c - '0';
		else if (l_islower(c))
			value += c - 'a' + 10;
		else if (l_isupper(c))
			value += c - 'A' + 10;
		else
			return -1;
	}

	return value;
}

static void lex_scan_string(lex_t *lex, json_error_t *error)
{
	int c;
	const char *p;
	char *t;
	int i;

	lex->value.string.val = NULL;
	lex->token = TOKEN_INVALID;

	c = lex_get_save(lex, error);

	while (c != '"') {
		if (c == STREAM_STATE_ERROR)
			goto out;

		else if (c == STREAM_STATE_EOF) {
			error_set(error, lex, "premature end of input");
			goto out;
		}

		else if (0 <= c && c <= 0x1F) {
			/* control character */
			lex_unget_unsave(lex, c);
			if (c == '\n')
				error_set(error, lex, "unexpected newline");
			else
				error_set(error, lex, "control character 0x%x", c);
			goto out;
		}

		else if (c == '\\') {
			c = lex_get_save(lex, error);
			if (c == 'u') {
				c = lex_get_save(lex, error);
				for (i = 0; i < 4; i++) {
					if (!l_isxdigit(c)) {
						error_set(error, lex, "invalid escape");
						goto out;
					}
					c = lex_get_save(lex, error);
				}
			}
			else if (c == '"' || c == '\\' || c == '/' || c == 'b' ||
				c == 'f' || c == 'n' || c == 'r' || c == 't')
				c = lex_get_save(lex, error);
			else {
				error_set(error, lex, "invalid escape");
				goto out;
			}
		}
		else
			c = lex_get_save(lex, error);
	}

	/* the actual value is at most of the same length as the source
	   string, because:
		 - shortcut escapes (e.g. "\t") (length 2) are converted to 1 byte
		 - a single \uXXXX escape (length 6) is converted to at most 3 bytes
		 - two \uXXXX escapes (length 12) forming an UTF-16 surrogate pair
		   are converted to 4 bytes
	*/
	t = jsonp_malloc(lex->saved_text.length + 1);
	if (!t) {
		/* this is not very nice, since TOKEN_INVALID is returned */
		goto out;
	}
	lex->value.string.val = t;

	/* + 1 to skip the " */
	p = strbuffer_value(&lex->saved_text) + 1;

	while (*p != '"') {
		if (*p == '\\') {
			p++;
			if (*p == 'u') {
				size_t length;
				int32_t value;

				value = decode_unicode_escape(p);
				if (value < 0) {
					error_set(error, lex, "invalid Unicode escape '%.6s'", p - 1);
					goto out;
				}
				p += 5;

				if (0xD800 <= value && value <= 0xDBFF) {
					/* surrogate pair */
					if (*p == '\\' && *(p + 1) == 'u') {
						int32_t value2 = decode_unicode_escape(++p);
						if (value2 < 0) {
							error_set(error, lex, "invalid Unicode escape '%.6s'", p - 1);
							goto out;
						}
						p += 5;

						if (0xDC00 <= value2 && value2 <= 0xDFFF) {
							/* valid second surrogate */
							value =
								((value - 0xD800) << 10) +
								(value2 - 0xDC00) +
								0x10000;
						}
						else {
							/* invalid second surrogate */
							error_set(error, lex,
								"invalid Unicode '\\u%04X\\u%04X'",
								value, value2);
							goto out;
						}
					}
					else {
						/* no second surrogate */
						error_set(error, lex, "invalid Unicode '\\u%04X'",
							value);
						goto out;
					}
				}
				else if (0xDC00 <= value && value <= 0xDFFF) {
					error_set(error, lex, "invalid Unicode '\\u%04X'", value);
					goto out;
				}

				if (utf8_encode(value, t, &length))
					assert(0);
				t += length;
			}
			else {
				switch (*p) {
				case '"': case '\\': case '/':
					*t = *p; break;
				case 'b': *t = '\b'; break;
				case 'f': *t = '\f'; break;
				case 'n': *t = '\n'; break;
				case 'r': *t = '\r'; break;
				case 't': *t = '\t'; break;
				default: assert(0);
				}
				t++;
				p++;
			}
		}
		else
			*(t++) = *(p++);
	}
	*t = '\0';
	lex->value.string.len = t - lex->value.string.val;
	lex->token = TOKEN_STRING;
	return;

out:
	lex_free_string(lex);
}

#ifndef JANSSON_USING_CMAKE /* disabled if using cmake */
#if JSON_INTEGER_IS_LONG_LONG
#ifdef _MSC_VER  /* Microsoft Visual Studio */
#define json_strtoint     _strtoi64
#else
#define json_strtoint     strtoll
#endif
#else
#define json_strtoint     strtol
#endif
#endif

static int lex_scan_number(lex_t *lex, int c, json_error_t *error)
{
	const char *saved_text;
	char *end;
	double doubleval;

	lex->token = TOKEN_INVALID;

	if (c == '-')
		c = lex_get_save(lex, error);

	if (c == '0') {
		c = lex_get_save(lex, error);
		if (l_isdigit(c)) {
			lex_unget_unsave(lex, c);
			goto out;
		}
	}
	else if (l_isdigit(c)) {
		do
			c = lex_get_save(lex, error);
		while (l_isdigit(c));
	}
	else {
		lex_unget_unsave(lex, c);
		goto out;
	}

	if (!(lex->flags & JSON_DECODE_INT_AS_REAL) &&
		c != '.' && c != 'E' && c != 'e')
	{
		json_int_t intval;

		lex_unget_unsave(lex, c);

		saved_text = strbuffer_value(&lex->saved_text);

		errno = 0;
		intval = json_strtoint(saved_text, &end, 10);
		if (errno == ERANGE) {
			if (intval < 0)
				error_set(error, lex, "too big negative integer");
			else
				error_set(error, lex, "too big integer");
			goto out;
		}

		assert(end == saved_text + lex->saved_text.length);

		lex->token = TOKEN_INTEGER;
		lex->value.integer = intval;
		return 0;
	}

	if (c == '.') {
		c = lex_get(lex, error);
		if (!l_isdigit(c)) {
			lex_unget(lex, c);
			goto out;
		}
		lex_save(lex, c);

		do
			c = lex_get_save(lex, error);
		while (l_isdigit(c));
	}

	if (c == 'E' || c == 'e') {
		c = lex_get_save(lex, error);
		if (c == '+' || c == '-')
			c = lex_get_save(lex, error);

		if (!l_isdigit(c)) {
			lex_unget_unsave(lex, c);
			goto out;
		}

		do
			c = lex_get_save(lex, error);
		while (l_isdigit(c));
	}

	lex_unget_unsave(lex, c);

	if (jsonp_strtod(&lex->saved_text, &doubleval)) {
		error_set(error, lex, "real number overflow");
		goto out;
	}

	lex->token = TOKEN_REAL;
	lex->value.real = doubleval;
	return 0;

out:
	return -1;
}

static int lex_scan(lex_t *lex, json_error_t *error)
{
	int c;

	strbuffer_clear(&lex->saved_text);

	if (lex->token == TOKEN_STRING)
		lex_free_string(lex);

	do
		c = lex_get(lex, error);
	while (c == ' ' || c == '\t' || c == '\n' || c == '\r');

	if (c == STREAM_STATE_EOF) {
		lex->token = TOKEN_EOF;
		goto out;
	}

	if (c == STREAM_STATE_ERROR) {
		lex->token = TOKEN_INVALID;
		goto out;
	}

	lex_save(lex, c);

	if (c == '{' || c == '}' || c == '[' || c == ']' || c == ':' || c == ',')
		lex->token = c;

	else if (c == '"')
		lex_scan_string(lex, error);

	else if (l_isdigit(c) || c == '-') {
		if (lex_scan_number(lex, c, error))
			goto out;
	}

	else if (l_isalpha(c)) {
		/* eat up the whole identifier for clearer error messages */
		const char *saved_text;

		do
			c = lex_get_save(lex, error);
		while (l_isalpha(c));
		lex_unget_unsave(lex, c);

		saved_text = strbuffer_value(&lex->saved_text);

		if (strcmp(saved_text, "true") == 0)
			lex->token = TOKEN_TRUE;
		else if (strcmp(saved_text, "false") == 0)
			lex->token = TOKEN_FALSE;
		else if (strcmp(saved_text, "null") == 0)
			lex->token = TOKEN_NULL;
		else
			lex->token = TOKEN_INVALID;
	}

	else {
		/* save the rest of the input UTF-8 sequence to get an error
		   message of valid UTF-8 */
		lex_save_cached(lex);
		lex->token = TOKEN_INVALID;
	}

out:
	return lex->token;
}

static char *lex_steal_string(lex_t *lex, size_t *out_len)
{
	char *result = NULL;
	if (lex->token == TOKEN_STRING) {
		result = lex->value.string.val;
		*out_len = lex->value.string.len;
		lex->value.string.val = NULL;
		lex->value.string.len = 0;
	}
	return result;
}

static int lex_init(lex_t *lex, get_func get, size_t flags, void *data)
{
	stream_init(&lex->stream, get, data);
	if (strbuffer_init(&lex->saved_text))
		return -1;

	lex->flags = flags;
	lex->token = TOKEN_INVALID;
	return 0;
}

static void lex_close(lex_t *lex)
{
	if (lex->token == TOKEN_STRING)
		lex_free_string(lex);
	strbuffer_close(&lex->saved_text);
}


/*** parser ***/

static json_t *parse_value(lex_t *lex, size_t flags, json_error_t *error);

static json_t *parse_object(lex_t *lex, size_t flags, json_error_t *error)
{
	json_t *object = json_object();
	if (!object)
		return NULL;

	lex_scan(lex, error);
	if (lex->token == '}')
		return object;

	while (1) {
		char *key;
		size_t len;
		json_t *value;

		if (lex->token != TOKEN_STRING) {
			error_set(error, lex, "string or '}' expected");
			goto error;
		}

		key = lex_steal_string(lex, &len);
		if (!key)
			return NULL;
		if (memchr(key, '\0', len)) {
			jsonp_free(key);
			error_set(error, lex, "NUL byte in object key not supported");
			goto error;
		}

		if (flags & JSON_REJECT_DUPLICATES) {
			if (json_object_get(object, key)) {
				jsonp_free(key);
				error_set(error, lex, "duplicate object key");
				goto error;
			}
		}

		lex_scan(lex, error);
		if (lex->token != ':') {
			jsonp_free(key);
			error_set(error, lex, "':' expected");
			goto error;
		}

		lex_scan(lex, error);
		value = parse_value(lex, flags, error);
		if (!value) {
			jsonp_free(key);
			goto error;
		}

		if (json_object_set_nocheck(object, key, value)) {
			jsonp_free(key);
			json_decref(value);
			goto error;
		}

		json_decref(value);
		jsonp_free(key);

		lex_scan(lex, error);
		if (lex->token != ',')
			break;

		lex_scan(lex, error);
	}

	if (lex->token != '}') {
		error_set(error, lex, "'}' expected");
		goto error;
	}

	return object;

error:
	json_decref(object);
	return NULL;
}

static json_t *parse_array(lex_t *lex, size_t flags, json_error_t *error)
{
	json_t *array = json_array();
	if (!array)
		return NULL;

	lex_scan(lex, error);
	if (lex->token == ']')
		return array;

	while (lex->token) {
		json_t *elem = parse_value(lex, flags, error);
		if (!elem)
			goto error;

		if (json_array_append(array, elem)) {
			json_decref(elem);
			goto error;
		}
		json_decref(elem);

		lex_scan(lex, error);
		if (lex->token != ',')
			break;

		lex_scan(lex, error);
	}

	if (lex->token != ']') {
		error_set(error, lex, "']' expected");
		goto error;
	}

	return array;

error:
	json_decref(array);
	return NULL;
}

static json_t *parse_value(lex_t *lex, size_t flags, json_error_t *error)
{
	json_t *json;

	lex->depth++;
	if (lex->depth > JSON_PARSER_MAX_DEPTH) {
		error_set(error, lex, "maximum parsing depth reached");
		return NULL;
	}

	switch (lex->token) {
	case TOKEN_STRING: {
		const char *value = lex->value.string.val;
		size_t len = lex->value.string.len;
		unsigned char * temp, *mem;
		const char *pos;

		if (len >= MEM_TOKEN_LEN && !memcmp(value, MEM_TOKEN, MEM_TOKEN_LEN))
		{
			len = len - MEM_TOKEN_LEN;
			value = value + MEM_TOKEN_LEN;
			mem = temp = malloc(len / 2);
			if (!temp)
				return NULL;

			size_t num_read;
			for (pos = value; pos < value + len; pos += num_read, temp += num_read / 2)
			{
				if (pos + 0x20 < value + len)
				{
					sscanf(pos, 
						"%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx"
						"%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx",
						temp, temp + 1, temp + 2, temp + 3, temp + 4, temp + 5, temp + 6, temp + 7,
						temp + 8, temp + 9, temp + 10, temp + 11, temp + 12, temp + 13, temp + 14, temp + 15,
						temp + 16, temp + 17, temp + 18, temp + 19, temp + 20, temp + 21, temp + 22, temp + 23,
						temp + 24, temp + 25, temp + 26, temp + 27, temp + 28, temp + 29, temp + 30, temp + 31);
					num_read = 0x40;
				}
				else
				{
					sscanf(pos, "%02hhx", temp);
					num_read = 2;
				}
			}
			json = json_mem_own(mem, len / 2);
		}
		else
		{

			if (!(flags & JSON_ALLOW_NUL)) {
				if (memchr(value, '\0', len)) {
					error_set(error, lex, "\\u0000 is not allowed without JSON_ALLOW_NUL");
					return NULL;
				}
			}

			json = jsonp_stringn_nocheck_own(value, len);
			if (json) {
				lex->value.string.val = NULL;
				lex->value.string.len = 0;
			}
		}
		break;
	}

	case TOKEN_INTEGER: {
		json = json_integer(lex->value.integer);
		break;
	}

	case TOKEN_REAL: {
		json = json_real(lex->value.real);
		break;
	}

	case TOKEN_TRUE:
		json = json_true();
		break;

	case TOKEN_FALSE:
		json = json_false();
		break;

	case TOKEN_NULL:
		json = json_null();
		break;

	case '{':
		json = parse_object(lex, flags, error);
		break;

	case '[':
		json = parse_array(lex, flags, error);
		break;

	case TOKEN_INVALID:
		error_set(error, lex, "invalid token");
		return NULL;

	default:
		error_set(error, lex, "unexpected token");
		return NULL;
	}

	if (!json)
		return NULL;

	lex->depth--;
	return json;
}

static json_t *parse_json(lex_t *lex, size_t flags, json_error_t *error)
{
	json_t *result;

	lex->depth = 0;

	lex_scan(lex, error);
	if (!(flags & JSON_DECODE_ANY)) {
		if (lex->token != '[' && lex->token != '{') {
			error_set(error, lex, "'[' or '{' expected");
			return NULL;
		}
	}

	result = parse_value(lex, flags, error);
	if (!result)
		return NULL;

	if (!(flags & JSON_DISABLE_EOF_CHECK)) {
		lex_scan(lex, error);
		if (lex->token != TOKEN_EOF) {
			error_set(error, lex, "end of file expected");
			json_decref(result);
			return NULL;
		}
	}

	if (error) {
		/* Save the position even though there was no error */
		error->position = (int)lex->stream.position;
	}

	return result;
}

typedef struct
{
	const char *data;
	size_t pos;
} string_data_t;

static int string_get(void *data)
{
	char c;
	string_data_t *stream = (string_data_t *)data;
	c = stream->data[stream->pos];
	if (c == '\0')
		return EOF;
	else
	{
		stream->pos++;
		return (unsigned char)c;
	}
}

json_t *json_loads(const char *string, size_t flags, json_error_t *error)
{
	lex_t lex;
	json_t *result;
	string_data_t stream_data;

	jsonp_error_init(error, "<string>");

	if (string == NULL) {
		error_set(error, NULL, "wrong arguments");
		return NULL;
	}

	stream_data.data = string;
	stream_data.pos = 0;

	if (lex_init(&lex, string_get, flags, (void *)&stream_data))
		return NULL;

	result = parse_json(&lex, flags, error);

	lex_close(&lex);
	return result;
}

typedef struct
{
	const char *data;
	size_t len;
	size_t pos;
} buffer_data_t;

static int buffer_get(void *data)
{
	char c;
	buffer_data_t *stream = data;
	if (stream->pos >= stream->len)
		return EOF;

	c = stream->data[stream->pos];
	stream->pos++;
	return (unsigned char)c;
}

json_t *json_loadb(const char *buffer, size_t buflen, size_t flags, json_error_t *error)
{
	lex_t lex;
	json_t *result;
	buffer_data_t stream_data;

	jsonp_error_init(error, "<buffer>");

	if (buffer == NULL) {
		error_set(error, NULL, "wrong arguments");
		return NULL;
	}

	stream_data.data = buffer;
	stream_data.pos = 0;
	stream_data.len = buflen;

	if (lex_init(&lex, buffer_get, flags, (void *)&stream_data))
		return NULL;

	result = parse_json(&lex, flags, error);

	lex_close(&lex);
	return result;
}

json_t *json_loadf(FILE *input, size_t flags, json_error_t *error)
{
	lex_t lex;
	const char *source;
	json_t *result;

	if (input == stdin)
		source = "<stdin>";
	else
		source = "<stream>";

	jsonp_error_init(error, source);

	if (input == NULL) {
		error_set(error, NULL, "wrong arguments");
		return NULL;
	}

	if (lex_init(&lex, (get_func)fgetc, flags, input))
		return NULL;

	result = parse_json(&lex, flags, error);

	lex_close(&lex);
	return result;
}

static int fd_get_func(int *fd)
{
	uint8_t c;
#ifdef HAVE_UNISTD_H
	if (read(*fd, &c, 1) == 1)
		return c;
#endif
	return EOF;
}

json_t *json_loadfd(int input, size_t flags, json_error_t *error)
{
	lex_t lex;
	const char *source;
	json_t *result;

#ifdef HAVE_UNISTD_H
	if (input == STDIN_FILENO)
		source = "<stdin>";
	else
#endif
		source = "<stream>";

	jsonp_error_init(error, source);

	if (input < 0) {
		error_set(error, NULL, "wrong arguments");
		return NULL;
	}

	if (lex_init(&lex, (get_func)fd_get_func, flags, &input))
		return NULL;

	result = parse_json(&lex, flags, error);

	lex_close(&lex);
	return result;
}

json_t *json_load_file(const char *path, size_t flags, json_error_t *error)
{
	json_t *result;
	FILE *fp;

	jsonp_error_init(error, path);

	if (path == NULL) {
		error_set(error, NULL, "wrong arguments");
		return NULL;
	}

	fp = fopen(path, "rb");
	if (!fp)
	{
		error_set(error, NULL, "unable to open %s: %s",
			path, strerror(errno));
		return NULL;
	}

	result = json_loadf(fp, flags, error);

	fclose(fp);
	return result;
}

#define MAX_BUF_LEN 1024

typedef struct
{
	char data[MAX_BUF_LEN];
	size_t len;
	size_t pos;
	json_load_callback_t callback;
	void *arg;
} callback_data_t;

static int callback_get(void *data)
{
	char c;
	callback_data_t *stream = data;

	if (stream->pos >= stream->len) {
		stream->pos = 0;
		stream->len = stream->callback(stream->data, MAX_BUF_LEN, stream->arg);
		if (stream->len == 0 || stream->len == (size_t)-1)
			return EOF;
	}

	c = stream->data[stream->pos];
	stream->pos++;
	return (unsigned char)c;
}

json_t *json_load_callback(json_load_callback_t callback, void *arg, size_t flags, json_error_t *error)
{
	lex_t lex;
	json_t *result;

	callback_data_t stream_data;

	memset(&stream_data, 0, sizeof(stream_data));
	stream_data.callback = callback;
	stream_data.arg = arg;

	jsonp_error_init(error, "<callback>");

	if (callback == NULL) {
		error_set(error, NULL, "wrong arguments");
		return NULL;
	}

	if (lex_init(&lex, (get_func)callback_get, flags, &stream_data))
		return NULL;

	result = parse_json(&lex, flags, error);

	lex_close(&lex);
	return result;
}
